Implements the Synced Notifications Welcome Toast.

The first notification for synced notifications will
now generate a normal notification explaining the new
service.

This does not yet implement click-to-disable or have
proper resources.

BUG=315248

Review URL: https://codereview.chromium.org/140053003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@246120 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 246120
Adds the new image for display notifications.

BUG=254737
R=oshima@chromium.org
TEST=manually

Review URL: https://codereview.chromium.org/141653004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@246122 0039d316-1c4b-4281-b951-d872f2087c98
gn: Fix clang plugin on ios.

BUG=336491
TBR=brettw@chromium.org

Review URL: https://codereview.chromium.org/144073003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@246124 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 246124